What RobynsVeil said sounds like perfectly comprehensible English to me, but if it needs spelling out... When character's eyes "stand out - sparkle", mostly this is due to reflections in the eyes. There are essentially three ways to get reflections in the eyes.

1. Paint them into the texture map.
2. Paint them in during post-work.
3. In Poser, arrange the lighting scenery and materials in such a way that the eyes have "real" reflections from the environment (lights and or scenery).

Highlights created by the first two methods are often referred to as "Burnt-in" by analogy to the photographic technique of the same name. Unless you are a skilled painter, it is usually much easier to achieve realistic reflections via the last method. Reflections created via the first method almost never look natural.

 

So to sum up. Good lighting, attention to the environment, good shaders for the eye materials, and often a certain amount of post-work, are elements that go to making the eyes look good.